Vertical-cavity surface-emitting lasers (VCSELs) are known to have advantages of lower threshold current operation, circular and low-divergence output beam, and lower temperature sensitivity compared to edge-emitting laser diodes. In conventional VCSELs, the formation of a current aperture plays a vital role in the device characteristics. Low laser thresholds and single-transverse-mode operation would not be possible without a well-defined current aperture to confine carriers to generate photons between the two distributed Bragg reflectors. Since the introduction of the controlled oxidation process for the AlxGa1-xAs material system by Dallesasse and Holonyak in 1989, most VCSELs have employed oxidation for current aperture formation as well as optical confinement and this technique has become one of the most commonly used fabrication techniques for traditional III-V compound semiconductor infrared VCSELs. However, for III-N emitters operating at wavelengths in the ultraviolet to green wavelength range, the formation of Al-based native oxide layers has not proven feasible. As a result, various current-confinement techniques have been studied such as, selective-area growth of buried AlN, oxidizing AlInN, and selective activation of acceptors.
In this work, we report an ion-implantation process which is effective for carrier confinement and defines a current aperture for our III-N ultraviolet microcavity light-emitting diodes (MCLEDs). The devices have peak emission wavelength of ~371.4 nm with the spectral linewidth of 5.1 nm at the highest pulsed current injection level of 15 kA/cm2. Further discussion on the material growth, material characterization, implantation parameters, as well as numerical simulation for structural design will be presented in the conference.